As known, a fuel cell produces electricity through an electrochemical reaction between hydrogen and oxygen. The fuel cell may continuously produce electrical energy upon receiving a chemical reactant from outside without having a separate charging process.
The fuel cell may include separators (or bipolar plates) which are disposed on both sides of a membrane-electrode assembly (MEA) therebetween. A plurality of fuel cells may be arranged to form a fuel cell stack.
Here, the membrane-electrode assembly that is an example of a core component of the fuel cell as a three-layer structure, includes an electrolytic membrane in which hydrogen ions transfer, an anode catalyst electrode layer formed on one surface of the electrolytic membrane, and a cathode catalyst electrode layer formed on the other surface of the electrolytic membrane. A direct coating method and a decal method are examples of a method of manufacturing the three-layer structure membrane-electrode assembly.
In a roll-to-roll process for unwinding an electrolyte membrane wound in a roll form and forming a catalyst electrode layer on both surfaces of the electrolyte membrane, a method for directly coating a catalyst slurry on the electrolyte membrane cannot be employed because of a low (or poor) property of the electrolyte membrane.
Thus, the catalyst electrode layer cannot be directly coated on the electrolyte membrane in a roll-to-roll process according to a related art so that the decal method for transferring the catalyst electrode layer on the electrolyte membrane is used after the catalyst electrode layer is coated on a separate release film.
In the decal method, an release film of a roll type coated with each catalyst electrode layer and an electrolyte membrane of a roll type pass a bonding roll of high temperature and high pressure to be laminated (thermally compressed), and the release film is removed so that the membrane-electrode assembly of the three-layer structure is manufactured.
However, in the decal method using the roll lamination process, in a state in which the release film coated with each catalyst electrode layer on both sides via the electrolyte membrane interposed therebetween is positioned, since they pass between the bonding rolls of high temperature and high pressure and the catalyst electrode layer and the electrolyte membrane are laminated in the directions such that they contact each other, it is difficult to align the lamination positions of the anode catalyst electrode layer and the cathode catalyst electrode layer.
In other words, the release film and the electrolyte membrane continuously pass between the bonding rolls of high temperature and high pressure that are always pressed and the catalyst electrode layer is laminated on both surfaces of the electrolyte membrane, and in this roll laminating continuous process, it is difficult to correctly accord the lamination positions of the catalyst electrode layers by a feeding speed difference of the release film.
Another reason that the lamination positions of the anode catalyst electrode layer and the cathode catalyst electrode layer are difficult to align is because a pitch between the catalyst electrode layers is not constant in the process of manufacturing the catalyst electrode layer of the continuous patterns by coating the catalyst slurry to the release film.
Thus, when the membrane-electrode assembly (MEA) is manufactured by the decal method according to a related art, a failure rate is very high and production rate of the MEA is low so that productivity is reduced.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.